Osven, a Philosopher of the Knife and self-proclaimed Demon Hunter, was involved the Raid on Maelshyve's Fortress in the year 426 AV. Through various means, he provided necromantic alchemical vials, similar to the necromantic alchemical solution used against Lyras. These vials when used against Ciriasa damaged Maelshyve's hold over her, and eventually allowed Ciriasa to be restored to human form, preventing Maelshyve from strengthening her position. In the fight, Ciriasa was slain, her soul lost, and Osven absconded with the corpse of Ciriasa, neither being seen again for some time.
Maelshyve began to regroup. In 430 AV, as she was courted by some and challenged by others, Osven returned with news that through collaboration with other magical scholars, and through study of Ciriasa's remains, he had improved upon the designs of the vials, and created a device which he believed was capable of harming Maelshyve and forcing her out of the Plane of Abiding.
Osven began to recruit people to his cause. Maelshyve began to once again reach for a foothold in the Plane of Abiding.
The device, called the Philosopher's Knot, was revealed to actually be a pair, and they were handed off to adventurers who lead two parties, one heading into Maelshyve's Fortress and the other to the Abyssal Seed. Once implanted, both devices required a large effort to activate, and adventurers quite impressively finished the task in relatively short order. The devices activated, and tunneled into the Soul of Maelshyve, eventually finding their way to the core of her psyche, her purpose.
At their final activation, the devices began to do their work, and Maelshyve reached out with one last effort to destroy them, trapping every one present in her domain. At the zero hour, Osven sacrificed himself, using his own life force to force Maelshyve back and empower the devices, which shackled and reduced her. This opened a final area, the Pith, in which the last of her dying essence can be battled in the form of ur-maeldryths.
What remains of Osven is still within the Philsopher's Knot, and still screaming.
You see Demon Hunter Osven, a Human.
Osven has a square-jawed face, jade eyes and a classical nose. His light brown hair is short and straight. He has tanned skin and an athletic build.
He is a bit over average height for a Human.
He appears to be in his prime.
He is in good shape.
He is wearing a cowl-like hood, a lever-drawn light crossbow, a rugged backpack, a damite chain hauberk, a small crusty barkhide shield sealed with protective wax, a small steel skinning knife with a leather-wrapped hilt, an Ilithian cedar parry stick, some faded pants, a thigh quiver dyed in a brown and green camouflage pattern and a pair of forest green boots caked in dried mud.